1. Field of the Invention
The present invention relates generally to mission configurable infrared countermeasures for aircraft, and more particularly to a deployment device which accommodates infrared decoy foils within multiple canisters so as to allow for the control dispensing and dispersal of the foils. The infrared foils are typically a Special Material (SM) which, when brought into contact with air, become warm and radiate infrared energy.
2. Description of the Related Art
As is well known in the prior art, military aircraft are typically provided with countermeasures which are used to draw various types of guided weapons away from the aircraft. One common prior art countermeasure is a flare which is adapted to attract infrared or heat seeking guided missiles away from the deploying aircraft. In this respect, the flare is designed to present a larger thermal target than the aircraft from which it is deployed, thus attracting the weapon away from the aircraft.
With continuing advances in weapons technology, flares have become less effective as countermeasures due to anti-aircraft weaponry having become more sophisticated and provided with enhanced capabilities to discriminate between flares and the deploying aircraft. In this respect, modem heat seeking missiles are typically provided with both a spectral discriminator which is adapted to sense the peak intensity wavelength of the infrared signature of the aircraft and a kinetic discriminator which is adapted to sense the speed and trajectory at which the infrared signature is traveling. When a conventional flare is deployed from the aircraft, the infrared signature produced thereby is typically more intense in the near visible wavelength than that produced by the engines of the aircraft. In addition, the velocity and trajectory of the flare is significantly different than that of the deploying aircraft since the flare, once deployed, slows rapidly and falls toward the ground. The spectral discriminator of the guided missile is adapted to distinguish between the infrared signature produced by the flare and that produced by the engines of the aircraft. Additionally, the kinetic discriminator of the guided missile is adapted to distinguish between the velocity and trajectory of the aircraft and that of the flare, even if the spectral discriminator does not distinguish the infrared signatures produced thereby. As such, the combined functionality of the spectral and kinetic discriminators of the guided missile typically succeeds in causing the guided missile to disregard the deployed flare, and continue to target the aircraft.
In view of the above-described shortcomings of conventional flares, there has been developed in the prior art countermeasure systems which are adapted to create an infrared signature which is similar in magnitude or intensity to that produced by the aircraft engines, appears to travel at a velocity and trajectory commensurate to that of the aircraft, and can provide continuous protection while the aircraft is over threat territory. Examples of these prior art systems are shown and described in Applicant's U.S. Pat. Nos. 5,915,694 entitled DECOY UTILIZING INFRARED SPECIAL MATERIAL and 6,499,407 entitled PACKAGING METHOD FOR INFRARED SPECIAL MATERIAL, the disclosures of which are incorporated herein by reference.
These and other prior art references generally teach the dispensation of SM foils from an aircraft by stacking the SM foils in a canister and ejecting them either all at once using an explosive charge, or in small packets or continuously from a canister using a drive screw or similar device. The principle disadvantage of the all at once dispensation approach is that it provides only momentary protection in one intense cloud which does not follow the aircraft. This particular problem has been addressed by devices that dispense the SM foils approximately continuously such that the infrared cloud produced thereby appears to match the aircraft kinematics. Such continuous dispensation has been accomplished successfully in the prior art for relatively short stacks of SM foils through the use of a piston driven by a lead screw, and also by packaging the SM foils into small packets which engage a drive belt that drives them out of a corresponding canister.
However, in order to provide protection for an extended period of time, it is desirable to package the SM foils into canisters with more volume. While this can be accomplished by engaging individual packets of SM foils to a drive belt as described above, the method is more mechanically complex, less volume efficient and allows less flexibility in how the SM foils are dispensed than does a canister with a piston/lead screw. Unfortunately, the use of a piston/lead screw canister to facilitate the deployment of long columns of SM foils itself gives rise to certain problems. Existing piston/lead screw canisters typically comprise a hollow tube with a piston at one end, and spring fingers at the other. The SM foil stack is located between the piston and spring fingers. The purpose of the spring fingers is to retain the SM foils until such time as they are forced out of the canister by the piston. The stack of SM foils has a great deal of compliance. Since none of the SM foils are perfectly flat, the column acts as a spring. As the piston drives the SM foils out, the SM foil stack compresses against the spring fingers until they finally let go, at which time a large slug of SM foils is dispensed. This effect is minimal for short stacks of SM foils, but prevents controlled and uniform dispensing of long stacks of SM foils. The present invention, as will be described in more detail below, overcomes these and other deficiencies of the prior art.